Postmenopausal osteoporosis due to the ovarian hormone deficiency is the most common cause of bone loss in women. The disorder is prevented by the administration of exogenous estrogen hormones, i.e. by an appropriate Hormone Replacement Therapy (HRT). The synthetic estrogen hormones used for this purpose are potent drugs and, if not properly used, may be associated with side effects, especially by long term administration.
The incidence of fractures ascribable to osteoporosis is lower in Asia than in Western countries. This difference has been attributed to the extensive use of soy-based foods [1] and in particular to some isoflavones that are present in soybeans. In fact, the efficacy of the soy isoflavones (SIs) on the trophism of the bones in post-menopause was demonstrated in several clinical studies [2, 3, 4, 5] and is supported by studies in ovariectomized rats [6].
Soybeans contain mainly two isoflavones, genistin and daidzin. Genistin (MW 432.22) is the β-glucoside of genistein (MW 270.24). Daidzin (MW 416.23) is the β-glucoside of daidzein (MW 254.24). Genistin and daidzin are relatively large molecules; they are very water-soluble and highly polar. These properties hinder their absorption from the gastrointestinal tract and therefore the bioavailability of the estrogen moiety.
To be absorbed and rendered bioavailable, the SIs must be hydrolyzed to aglycons, i.e. separated from the glucoside component [7]. This takes place by the action of special enzymes, the glycosidases. However, the human gastrointestinal tract and that of many mammalians does not secrete glycosidases and therefore the isoflavones cannot be hydrolyzed to become bioavailable. Conversely, some micro-organisms of the intestinal flora and in particular some lactic acid bacteria, produce the glycosidases required for the mentioned hydrolytic process that is necessary for the absorption of the SIs [8, 9]. The presence of glycosidase-producing bacteria in the gastrointestinal tract is therefore the prerequisite for the absorption and the efficacy of the SIs.
The intestinal flora varies greatly between individuals and, even in the same subject, it varies in function of the diet, climate, drug therapies, diseases, etc. Thus, in many subjects, the glycosidase production by the intestinal flora can be scarce or even absent, jeopardizing the absorption of the SIs.
Object of the present invention is to provide a composition for oral administration, particularly as a dietary supplement, for the mitigation, relief, and/or prevention of climacteric and postmenopausal disorders affecting women in pre-, peri- and post-menopause, including dismetabolism of bones that causes bone loss and structural changes with an increases of fracture risk.